The present invention relates generally to the regeneration of sorghum involving organogenesis. More specifically, the present invention relates to a method of regenerating sorghum, particularly Sorghum bicolor (L.) Moench, via organogenesis that yields a high frequency of regenerants.
The publications and other materials used herein to illuminate the background of the invention, and in particular, cases to provide additional details respecting the practice, are incorporated by reference, and for convenience are referenced in the following text by author and date and are listed alphabetically by author in the appended bibliography.
Sorghum (Sorghum bicolor (L.) Moench) is a widely grown grain and forage crop, and more closely related to the major crops of tropical origin such as rice, maize, sugarcane, and pearl millet. Sorghum ranks fifth in production among cereal crops, and is an important model for tropical grasses. It is unique among major cereals because it adapts well to environmental extremes, notably drought and heat. These attributes make sorghum the logical grain to support human and animal populations in areas with extreme heat and minimal precipitation (Howe et al. 2006). In addition, the current economic, environmental and energy security concerns worldwide forces to shift from fossil fuels to biofuel alternatives such as bioethanol and biodiesel. Since biofuels can be produced from a diverse set of crops, each country is adopting a strategy that exploits the comparative advantages it holds in certain crops.
Among the different biofuel crops, sorghum is considered to be a better candidate for the production of bioethanol because of the physiological and natural factors, including the fact that it is a photosynthetic efficient C4 plant. To further improve this crop, biotechnological techniques such as tissue culture and transformation can be utilized. Over three decades several reports were documented on sorghum regeneration using various explants using different composition of media. These reports include plant regeneration (immature embryos (Gamborg et al. 1977, Ma et al. 1987, Hagio 2002), shoot portions of mature embryos (Cai et al. 1987), Shoot apices (Zhong et al. 1988), mature embryos (Nirwan and Kothari, 2003), transverse thin layer cells of roots (Baskaran et al. 2006)), somatic embryogenesis (immature and mature embryos (Rao et al. 1995, Elkonin et al. 1996, MacKinnon et al. 1986), leaf base (Mishra and khurana, 2003)) and transformation (immature embryos (Zhao et al. 2000, Carvalho et al. 2004), immature and mature embryos, shoot tips and embryogenic callus (Tadesse et al. 2003) and shoot apices (Girijashankar et al. 2005), seeds (Howe et al. 2006)) in sorghum.
Despite these reported successes, it is desired to develop new techniques for the regeneration of sorghum. It is imperative that such techniques have high frequencies of regeneration which makes the techniques useful for the application of genetic manipulations such as biomass increase or sugar content increase to improve this crop for increased bioethanol production.